STUNNER: Robert Ellis (above) was found guilty only of weapon possession last night in the murder of Russel Timoshenko (below).

In a shocking verdict last night, a Brooklyn jury let one of three suspects off the hook for the murder of rookie Police Officer Russel Timoshenko, convicting him only of weapons possession.

Scores of uniformed cops sat in stunned silence as the panel's foreman announced not-guilty verdicts for 35-year-old Robert Ellis on the charges of aggravated murder and attempted murder for the July 9, 2007, Crown Heights shooting that mortally wounded Timoshenko and injured his partner, Herman Yan.

The slain officer's mother initially showed no reaction, even as other family members bowed their heads and grimaced.

But as Justice Plummer Lott dismissed the seven-woman, five-man jury and thanked them for their service, Tatyana Timoshenko wiped tears from her face.

Ellis was returned to jail to await sentencing next month on the three counts of criminal possession of a weapon on which he was convicted. He faces up to 15 years in prison on each - as opposed to life without parole for murder.

An enraged Patrick Lynch, president of the Patrolmen's Benevolent Association, said the verdict was an insult to every cop on the force.

"This mongrel today got off with murder," said Lynch. "There are no words to describe the anger that New York City police officers have today. You can imagine what the family is going through today."

Police Commissioner Ray Kelly said, "I am stunned and disappointed by the verdict. My prayers are with the Timoshenko family as they contend with this ordeal."

Assistant DA Mark Hale, who handled the Ellis case, laid his head down on the prosecution table as the jury filed out.

Jurors left quickly after deliberating for 10 hours, with one alternate slamming the decision.

"I tell you the son of a bitch was guilty," alternate Louis Viera told WNBC/Channel 4. "As guilty as you can ever be. He was in the car. He knew the guns were there. He killed a cop and he's walking. What justice is that?"

As the family members left the courtroom, Timoshenko's aunt, Inna Apanasyuk, burst into tears.

"For nothing! For nothing!" she cried. "He was taken in a second. Two seconds. No way. No way is this justice. This is a Broadway show."

Ellis maintained from the beginning that it was he - and not co-defendant Lee Woods - who was behind the wheel of the stolen BMW X5 when it was pulled over by Timoshenko and Yan.

Although three witnesses supported the prosecution's theory that Ellis was a shooter rather than the driver, some forensic evidence left that open to argument.

Ellis testified earlier this week that he fled the city and hid in Pennsylvania after the shooting because he feared the cops and thought he would meet the same fate as Sean Bell, who died in a hail of 50 police bullets outside a Queens strip club in November 2006.

A separate jury will continue deciding Woods' fate today, and another is set to hear summations in the case against Dexter Bostic, the other accused gunman.